package com.hmdp.service.impl;

import com.hmdp.dto.Result;
import com.hmdp.entity.VoucherOrder;
import com.hmdp.mapper.VoucherOrderMapper;
import com.hmdp.service.ISeckillVoucherService;
import com.hmdp.service.IVoucherOrderService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.RedisIdWorker;
import com.hmdp.utils.UserHolder;
import lombok.extern.slf4j.Slf4j;
import org.redisson.api.RLock;
import org.redisson.api.RedissonClient;
import org.springframework.aop.framework.AopContext;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.PostConstruct;
import javax.annotation.Resource;
import java.util.Collections;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Slf4j
@Service
public class VoucherOrderServiceImpl extends ServiceImpl<VoucherOrderMapper, VoucherOrder> implements IVoucherOrderService {

    @Resource
    private ISeckillVoucherService seckillVoucherService;

    @Resource
    private RedisIdWorker redisIdWorker;

    @Resource
    private StringRedisTemplate stringRedisTemplate;

    @Resource
    private RedissonClient redissonClient;

    //Spring Data Redis 执行 Lua 脚本
    private static final DefaultRedisScript<Long> SECKILL_SCRIPT;
    static {
        SECKILL_SCRIPT = new DefaultRedisScript<>();
        SECKILL_SCRIPT.setLocation(new ClassPathResource("seckill.lua"));
        SECKILL_SCRIPT.setResultType(Long.class);
    }

    private BlockingQueue<VoucherOrder> oredrTasks = new ArrayBlockingQueue<>(1024 * 1024);
    private static final ExecutorService SECKILL_ORDER_EXECUTOR = Executors.newSingleThreadExecutor();

    @PostConstruct
    private void init(){
        SECKILL_ORDER_EXECUTOR.submit(new VoucherOrderHandler());
    }

    private class VoucherOrderHandler implements Runnable{

        @Override
        public void run() {
            while(true){
                //1.获取队列中的订单信息
                try {
                    VoucherOrder voucherOrder = oredrTasks.take();
                    //2.创建订单
                    handleVoucherOrder(voucherOrder);
                } catch (Exception e) {
                    log.error("处理订单异常", e);
                }
            }
        }
    }

    private void handleVoucherOrder(VoucherOrder voucherOrder){
        // 1.获取用户
        Long userId = voucherOrder.getUserId();
        //2.创建锁对象
        RLock lock = redissonClient.getLock("lock:order" + userId);
        //3.获取锁
        boolean isLock = lock.tryLock();
        //4.判断是否获取锁成功
        if(!isLock){
            // 获取锁失败，返回错误信息
            log.error("不允许重复下单");
            return;
        }

        try {
            //获取代理对象（事务）
            proxy.creatVoucherOrder(voucherOrder);
        } catch (IllegalStateException e) {
            throw new RuntimeException(e);
        } finally {
            //释放锁
            lock.unlock();
        }

    }

    private IVoucherOrderService proxy;
    @Override
    //   @Transactional    //一共两张表操作，所以加上这个事务
    public Result seckillVoucher(Long voucherId) {
        //获取用户
        Long userId = UserHolder.getUser().getId();
        // 1.执行lua脚本
        Long result = stringRedisTemplate.execute(
                SECKILL_SCRIPT,
                Collections.emptyList(),
                voucherId.toString(), userId.toString()
        );
        // 2.判断结果是否为0
        int r = result.intValue();
        if(r != 0){
            //2.1 不为0，代表没有购买资格
            return  Result.fail(r == 1 ? "库存不足" : "不能重复下单");
        }
        //2.2 为0，有购买资格，把下单信息保存到阻塞队列
        VoucherOrder voucherOrder = new VoucherOrder();
        //2.3 订单id
        long orderId = redisIdWorker.nextId("order");
        voucherOrder.setId(orderId);
        //2.4 用户id
        voucherOrder.setUserId(userId);
        //2.5 代金券id
        voucherOrder.setVoucherId(voucherId);
        //2.6 放入阻塞队列
        oredrTasks.add(voucherOrder);

        //3.获取代理对象
        proxy = (IVoucherOrderService) AopContext.currentProxy();
        //4.返回订单Id
        return Result.ok(0);
    }

/*    @Override
 //   @Transactional    //一共两张表操作，所以加上这个事务
    public Result seckillVoucher(Long voucherId) {
        //1.查询优惠券
        SeckillVoucher voucher = seckillVoucherService.getById(voucherId);
        //2.判断秒杀是否开始
        if (voucher.getBeginTime().isAfter(LocalDateTime.now()))
        {
            // 未开始
            return Result.fail("秒杀未开始");
        }
        //3.判断秒杀是否已经结束
        if (voucher.getEndTime().isBefore(LocalDateTime.now())) {
            //已经结束
            return Result.fail("秒杀已经结束");
        }
        //4.判断库存是否充足
        if (voucher.getStock() < 1) {
            //库存不足
            return Result.fail("库存不足");
        }



        Long userId = UserHolder.getUser().getId();

        //如果按照以下方法，则调用的creatVoucherOrder没有事务功能
//        synchronized(userId.toString().intern()) {
//            return creatVoucherOrder(voucherId);
//        }

        //创建锁对象
//        SimpleRedisLock lock = new SimpleRedisLock("order" + userId, stringRedisTemplate);
        RLock lock = redissonClient.getLock("lock:order" + userId);
        //获取锁
        boolean isLock = lock.tryLock();
        //判断是否获取锁成功
        if(!isLock){
            // 获取锁失败，返回错误信息
            return Result.fail("一个人只允许下一单");
        }

        try {
            //获取代理对象（事务）
            IVoucherOrderService proxy = (IVoucherOrderService) AopContext.currentProxy();
            return proxy.creatVoucherOrder(voucherId);
        } catch (IllegalStateException e) {
            throw new RuntimeException(e);
        } finally {
            //释放锁
            lock.unlock();
        }

    }*/

/*    @Transactional
    public Result creatVoucherOrder(Long voucherId) {
        //5.一人一单
        Long userId = UserHolder.getUser().getId();

            //5.1  查询订单
            int count = query().eq("user_id", userId).eq("voucher_id", voucherId).count();
            //5.2  判断是否存在
            if (count > 0) {
                //  用户已经购买
                return Result.fail("用户已经购买过一次了！");
            }
            //6.扣减库存
            //以下这个应该涉及到了数据库的行级锁
            boolean success = seckillVoucherService.update()
                    .setSql("stock = stock - 1") // set stock = stock - 1
                    .eq("voucher_id", voucherId).gt("stock", 0) // where id = ? and stock > 0
                    .update();//第一张表操作
            if (!success) {
                //扣减失败
                return Result.fail("库存不足");
            }
            //7.创建订单
            VoucherOrder voucherOrder = new VoucherOrder();
            //7.1 订单id
            long orderId = redisIdWorker.nextId("order");
            voucherOrder.setId(orderId);
            //7.2 用户id
            voucherOrder.setUserId(userId);
            //7.3 代金券id
            voucherOrder.setVoucherId(voucherId);
            save(voucherOrder);//第二张表操作
            //7.返回订单id
            return Result.ok(orderId);
    }*/
@Transactional
public void creatVoucherOrder(VoucherOrder voucherOrder) {
    //5.一人一单
    Long userId = UserHolder.getUser().getId();

    //5.1  查询订单
    int count = query().eq("user_id", userId).eq("voucher_id", voucherOrder).count();
    //5.2  判断是否存在
    if (count > 0) {
        //  用户已经购买
        log.error("用户已经购买了一次！");
        return;
    }
    //6.扣减库存
    //以下这个应该涉及到了数据库的行级锁
    boolean success = seckillVoucherService.update()
            .setSql("stock = stock - 1") // set stock = stock - 1
            .eq("voucher_id", voucherOrder).gt("stock", 0) // where id = ? and stock > 0
            .update();//第一张表操作
    if (!success) {
        //扣减失败
        log.error("库存不足！");
        return;
    }
    //7.创建订单
    save(voucherOrder);//第二张表操作

}
}
